From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user pointers, v1 and v2, and swaps the words they point to in hand-written assembly. l.lwz r29,0(r4) l.lwz r27,0(r5) l.sw 0(r4),r27 l.sw 0(r5),r29 The pointers are not checked with access_ok(). The four memory accesses also have no exception table entries. A caller passes a kernel address as either pointer, and the syscall reads from and writes to it directly. This gives an unprivileged process a kernel read/write primitive. It overwrites kernel data such as the sys_call_table, gaining code execution in kernel context. Check both pointers before entering the critical section. Add fixups for the four memory accesses so faults on valid but unmapped user addresses return -EFAULT. [shorne@gmail.com: fix comment style] Fixes: 9d02a4283e9c ("OpenRISC: Boot code") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Stafford Horne --- io_uring/poll.h | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 io_uring/poll.h (limited to 'io_uring/poll.h') diff --git a/io_uring/poll.h b/io_uring/poll.h new file mode 100644 index 000000000..5647c5138 --- /dev/null +++ b/io_uring/poll.h @@ -0,0 +1,49 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include + +#define IO_POLL_ALLOC_CACHE_MAX 32 + +enum { + IO_APOLL_OK, + IO_APOLL_ABORTED, + IO_APOLL_READY +}; + +struct io_poll { + struct file *file; + struct wait_queue_head *head; + __poll_t events; + int retries; + struct wait_queue_entry wait; +}; + +struct async_poll { + struct io_poll poll; + struct io_poll *double_poll; +}; + +/* + * Must only be called inside issue_flags & IO_URING_F_MULTISHOT, or + * potentially other cases where we already "own" this poll request. + */ +static inline void io_poll_multishot_retry(struct io_kiocb *req) +{ + atomic_inc(&req->poll_refs); +} + +int io_poll_add_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe); +int io_poll_add(struct io_kiocb *req, unsigned int issue_flags); + +int io_poll_remove_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe); +int io_poll_remove(struct io_kiocb *req, unsigned int issue_flags); + +struct io_cancel_data; +int io_poll_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd, + unsigned issue_flags); +int io_arm_apoll(struct io_kiocb *req, unsigned issue_flags, __poll_t mask); +int io_arm_poll_handler(struct io_kiocb *req, unsigned issue_flags); +bool io_poll_remove_all(struct io_ring_ctx *ctx, struct io_uring_task *tctx, + bool cancel_all); + +void io_poll_task_func(struct io_tw_req tw_req, io_tw_token_t tw); -- cgit v1.3.1